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Zhang, Gang, Dejian Wang y Yuanchun Yu. "Investigation into the Effects of Straw Retention and Nitrogen Reduction on CH4 and N2O Emissions from Paddy Fields in the Lower Yangtze River Region, China". Sustainability 12, n.º 4 (24 de febrero de 2020): 1683. http://dx.doi.org/10.3390/su12041683.
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Straw retention is a widely used method in rice planting areas throughout China. However, the combined influences of straw retention and nitrogen (N) fertilizer application on greenhouse gas (GHG) fluxes from paddy fields merits significant attention. In this work, we conducted a field experiment in the lower Yangtze River region of China to study the effects of straw retention modes and N fertilizer rates on rice yield, methane (CH4) and nitrous oxide (N2O) emission fluxes, global warming potential (GWP), and greenhouse gas intensity (GHGI) during the rice season. The experiments included six treatments: the recommended N fertilizer—240 kg N·ha−1 with (1) no straw, (2) wheat straw, (3) rice straw, and (4) both wheat and rice straw retentions; in a yearly rice–wheat cropping system (N1, WN1, RN1, and WRN1, respectively); as well as both wheat and rice straw retentions with (5) no N fertilizer and (6) 300 kg N·ha−1 conventional N fertilizer (WRN0, WRN2). The results showed that CH4 emissions were mainly concentrated in the tillering fertilizer stage and accounted for 54.2%–87.5% of the total emissions during the rice season, and N2O emissions were primarily concentrated in the panicle fertilizer stage and accounted for 46.7%–51.4% total emissions. CH4 was responsible for 87.5%–98.5% of the total CH4 and N2O GWP during the rice season, and was the main GHG contributor in the paddy field. Although straw retention reduced N2O emissions from paddy field, it significantly increased CH4 emissions, which resulted in a significant net increase in the total GWP. Compared with the N1 treatment, the total GWP of WN1, WRN1, and RN1 increased by 3.45, 3.73, and 1.62 times, respectively; and the GHGI increased by 3.00, 2.96, and 1.52 times, respectively, so the rice straw retention mode had the smallest GWP and GHGI. Under double-season’s straw retentions, N fertilizer application increased both CH4 and N2O emissions, and the WRN1 treatment not only maintained high rice yield but also significantly reduced the GWP and GHGI by 16.5% and 30.1% (p < 0.05), respectively, relative to the WRN2 treatment. Results from this study suggest that adopting the “rice straw retention + recommended N fertilizer” mode (RN1) in the rice–wheat rotation system prevalent in the lower Yangtze River region will aid in mitigating the contribution of straw retention to the greenhouse effect.
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Arnold, Christin, Ramona Schweyen, Arne Boeckler y Jeremias Hey. "Retention Force of Removable Partial Dentures with CAD-CAM-Fabricated Telescopic Crowns". Materials 13, n.º 14 (20 de julio de 2020): 3228. http://dx.doi.org/10.3390/ma13143228.
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The aim of this study was to compare the retention forces after artificial aging of telescopic crowns fabricated either by a conventional lost-wax technique or by computer-aided design/computer-aided manufacturing (CAD-CAM) technology. Two types of telescopic crowns (0°) were fabricated conventionally using high-noble (group A) and non-precious metal (group B). CAD-CAM fabricated telescopic crowns (0°) were made of non-precious metal (group C). Retention forces were assessed before and after artificial aging and after axial and non-axial loading. Initially [I.] and after artificial aging [IV.], specimens of group C (I. 16.2 N; IV. 13.6 N) exhibited the highest retention forces. The retention forces in groups B (I. 12.5 N; IV. 4.6 N) and A (I. 9.6 N; IV. 2.9 N) were found to be lower than those of group C. The retention force differences between the groups were statistically significant (p < 0.001) at all measurement times [I. vs. IV.]. Different fabricated telescopic crowns with approximately identical designs and materials exhibited different retention forces and different long-term retentive behavior. An optimized CAD-CAM process with individually defined design parameters ensured telescopic crowns with a better fit. These findings might influence prospective clinical decision-making.
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Wollheim, Wilfred M., Brian A. Pellerin, Charles J. Vörösmarty y Charles S. Hopkinson. "N Retention in Urbanizing Headwater Catchments". Ecosystems 8, n.º 8 (28 de noviembre de 2005): 871–84. http://dx.doi.org/10.1007/s10021-005-0178-3.
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Devito, Kevin J. y Peter J. Dillon. "Importance of Runoff and Winter Anoxia to the P and N Dynamics of a Beaver Pond". Canadian Journal of Fisheries and Aquatic Sciences 50, n.º 10 (1 de octubre de 1993): 2222–34. http://dx.doi.org/10.1139/f93-248.
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Annual retentions of total phosphorus (TP) (−11%) and total nitrogen (TN) (−5%) of a headwater beaver pond in central Ontario were low during 1987–88. Annually, inputs exceeded outputs of total reactive P (71%) and NO3–N (35%), and outputs exceeded inputs of total unreactive P (−33%) and total organic N (−26%), and inputs approximated outputs of NH4–N (−8%). Seasonal trends in P and N retention were inversely correlated with runoff. Monthly retention was weakly positively related to average water temperature and redox potential (ORP). Positive monthly retention coincided with low runoff and high biotic assimilation during the growing season. Winter ice cover was associated with undetectable dissolved oxygen and low ORP and increased levels of P and N, particularly NH4–N. High levels of P and N in the surface water during winter were coupled with increased runoff and potentially low biotic assimilation resulting in a net release of TP and TN. Large flow-through of waterborne inputs and flushing of regenerated P and N occurred during peak snowmelt resulting in low annual retention. Initial accumulation of flooded forest material and input of organic matter by beaver may be very important to P and N dynamics, representing a long-term source of nutrients to the pond water and outflow.
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Chindarungruangrat, Atitiya, Trinuch Eiampongpaiboon y Bundhit Jirajariyavej. "Effect of Various Retentive Element Materials on Retention of Mandibular Implant-Retained Overdentures". Molecules 27, n.º 12 (19 de junio de 2022): 3925. http://dx.doi.org/10.3390/molecules27123925.
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This study aimed to examine the retentive characteristics of each retentive element material and the effects from thermocycling using the two implant-retained mandibular overdenture model. Two stud abutments and three retentive element materials; nylon, polyetheretherketone (PEEK) and polyvinylsiloxane (PVS) were used in this study. Four tested groups, with a total of 40 overdentures, were fabricated, including a Locator® abutment with nylon retention insert (NY), Novaloc® abutment with PEEK retention insert (PK), Locator® abutment with PVS retention insert (RL), and Novaloc® abutment with PVS retention insert (RN). The retentive force (N) was measured before thermocycling, and at 2500, 5000, and 10,000 cycles after thermocycling. Significant changes in the percentage of retention loss were found in the NY and PK groups (p < 0.05) at 6 and 12 months for the RL group (p < 0.05) after artificial aging. The RN group exhibited a constant retentive force (p > 0.05). The tendency of the percentage of retention loss significantly increased for PEEK, nylon, and PVS silicone over time. The results of the present study implied that retentive element materials tend to lose their retentive capability as a result of thermal undulation and water dispersion. Nylon and PEEK, comprising strong polar groups in polymer chains, showed a higher rate of retention loss than polyvinylsiloxane.
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Grimm, Nancy B., Richard W. Sheibley, Chelsea L. Crenshaw, Clifford N. Dahm, W. John Roach y Lydia H. Zeglin. "N retention and transformation in urban streams". Journal of the North American Benthological Society 24, n.º 3 (septiembre de 2005): 626–42. http://dx.doi.org/10.1899/04-027.1.
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KYLIN, ESKIL. "Über die N-Retention als blutdrucksteigernder Faktor". Acta Medica Scandinavica 58, n.º 1 (24 de abril de 2009): 342–49. http://dx.doi.org/10.1111/j.0954-6820.1923.tb15246.x.
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Hrouzek, Ján, Ján Krupčík y Ivan Skačáni. "Correlation Between GC Retention Data and Relative Molecular Weight of N,N-Bis(2,2,2-trifluoroethyl)dithiocarbamates of Some Divalent Metals". Collection of Czechoslovak Chemical Communications 61, n.º 11 (1996): 1609–14. http://dx.doi.org/10.1135/cccc19961609.
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The correlation of gas-chromatographic retention data (retention times and linear retention indices) and relative molecular weight was examined for N,N-bis(2,2,2-trifluoroethyl)dithiocarbamate chelates of some divalent metals. Regression analysis of data obtained by capillary GC on a non-polar column heated by applying a dual-ramp temperature programme gave linear dependences possessing reasonable correlation coefficients.
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Tesař, M., O. Syrovátka, M. Šír, Ľ. Lichner, J. Váchal y M. Krejča. "Storm runoff in the foothill headwater area Senotín". Soil and Water Research 3, No. 3 (31 de octubre de 2008): 168–74. http://dx.doi.org/10.17221/6/2008-swr.
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The purpose of the pilot project Senotín (1993–2000) was to prove the methods of revitalization of sub-mountain headwater area (0.38 km<sup>2</sup>) in the Novobystřická Vysočina Highland (610–725 m a. s. l.) in the Czech Republic. This area was tile-drained and ploughed in 1985. Seven underground clay shields newly constructed in 1995 stopped the function of the tile drainage. Four balks prevented the surface and subsurface runoff. These adaptations improved water retention capacity of the whole catchment, which is demonstrated using an example of runoff formation in the revitalized area. A typical storm rain (total 15 mm, duration 5.6 h, max. intensity 4 mm/20 min) and the consequent runoff was analysed, including the role of the soil in the runoff retardation and water retention. The runoff started in two hours since the rain beginning. The retention reached 98% of the rain total. The runoff lasted for 85 h. The concave-upward shape of the falling hydrograph limb indicates that the maximum retention capacity of the studied catchment is high.
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Ritz, Stephanie y Helmut Fischer. "A Mass Balance of Nitrogen in a Large Lowland River (Elbe, Germany)". Water 11, n.º 11 (14 de noviembre de 2019): 2383. http://dx.doi.org/10.3390/w11112383.
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Nitrogen (N) delivered by rivers causes severe eutrophication in many coastal waters, and its turnover and retention are therefore of major interest. We set up a mass balance along a 582 km river section of a large, N-rich lowland river to quantify N retention along this river segment and to identify the underlying processes. Our assessments are based on four Lagrangian sampling campaigns performed between 2011 and 2013. Water quality data served as a basis for calculations of N retention, while chlorophyll-a and zooplankton counts were used to quantify the respective primary and secondary transformations of dissolved inorganic N into biomass. The mass balance revealed an average N retention of 17 mg N m−2 h−1 for both nitrate N (NO3–N) and total N (TN). Stoichiometric estimates of the assimilative N uptake revealed that, although NO3–N retention was associated with high phytoplankton assimilation, only a maximum of 53% of NO3–N retention could be attributed to net algal assimilation. The high TN retention rates in turn were most probably caused by a combination of seston deposition and denitrification. The studied river segment acts as a TN sink by retaining almost 30% of the TN inputs, which shows that large rivers can contribute considerably to N retention during downstream transport.
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Abdollahi, M. Reza, Markus Wiltafsky-Martin y Velmurugu Ravindran. "Application of Apparent Metabolizable Energy versus Nitrogen-Corrected Apparent Metabolizable Energy in Poultry Feed Formulations: A Continuing Conundrum". Animals 11, n.º 8 (22 de julio de 2021): 2174. http://dx.doi.org/10.3390/ani11082174.
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In the present investigation, N retention, AME, and AMEn data from six energy evaluation assays, involving four protein sources (soybean meal, full-fat soybean, rapeseed meal and maize distiller’s dried grains with solubles [DDGS]), are reported. The correction for zero N retention, reduced the AME value of soybean meal samples from different origins from 9.9 to 17.8% with increasing N retention. The magnitude of AME penalization in full-fat soybean samples, imposed by zero N correction, increased from 1.90 to 9.64% with increasing N retention. The Δ AME (AME minus AMEn) in rapeseed meal samples increased from 0.70 to 1.09 MJ/kg as N-retention increased. In maize DDGS samples, the correction for zero N retention increased the magnitude of AME penalization from 5.44 to 8.21% with increasing N retention. For all protein sources, positive correlations (p < 0.001; r = 0.831 to 0.991) were observed between the N retention and Δ AME. The present data confirms that correcting AME values to zero N retention for modern broilers penalizes the energy value of protein sources and is of higher magnitude for ingredients with higher protein quality. Feed formulation based on uncorrected AME values could benefit least cost broiler feed formulations and merits further investigation.
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Király, Z., T. Körtvélyesi, L. Seres y M. Görgényi. "Structure-retention relationships in the gas chromatography of N,N-dialkylhydrazones". Chromatographia 42, n.º 11-12 (junio de 1996): 653–59. http://dx.doi.org/10.1007/bf02267697.
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Williams, P. E. V., G. M. Innes, K. Ogden y S. James. "The effects of a combination of the β agonist clenbuterol and bovine pituitary growth hormone on growth of milk-fed calves". Proceedings of the British Society of Animal Production (1972) 1987 (marzo de 1987): 54. http://dx.doi.org/10.1017/s0308229600034905.
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Clenbuterol, a β adrenergic agonist has been shown to increase nitrogen retention and decrease lipid deposition in cattle, sheep, pigs, poultry and laboratory rodents. Effects on nitrogen retention occur primarily in skeletal muscle (Williams et al 1987) and results suggest that reduced protein degradation is mainly responsible for the increased N retention. Reductions in N excretion were insufficient to account for the increased N retention in muscle and we demonstrated (Williams et al 1987) that increased N retention in skeletal muscle was occurring partly as a result of a nitrogen repartitioning in the body with reduced N retention in the viscera. Growth hormone also stimulates skeletal and muscle growth furthermore the mechanism whereby growth hormone stimulates N retention was considered to act primarily via a stimulation of protein synthesis (Eismann et al 1986). It would therefore appear that clenbuterol and growth hormone both increase N retention but by different mechanisms leading to the possibility of achieving an additive effect from the use of the two compounds in combination. The present experiment was designed to study the effects of clenbuterol and growth hormone individually and in combination on the N balance, creatinine excretion, protein and lipid accretion of veal calves.
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Bognár, Eszter, Tibor Balázs, György Ring, Barnabás Szabó y Péter Nagy. "Stent Retention Measurement". Materials Science Forum 659 (septiembre de 2010): 283–88. http://dx.doi.org/10.4028/www.scientific.net/msf.659.283.
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This article introduces two original measurement methods (i.e. adhesive layer and pulloff edge) for the determination of the stent retention force, together with the results from these measurements. The measurement with the adhesive layer models and quantifies the stentobstruction occurring in the constrictions; meanwhile the pull-off edge method is based on modelling and quantifying the collisions and constrictions in the main catheter. For the evaluation of the measurements our research introduced the specific ‘stent pull-off’ force, which shows the force required for the ‘pull-off’ of the stent from the balloon, which is referred to as the stent unit length. This is the maximum force value shown on the retention diagram (insert diagram reference here). It is ascertainable, that the presence of the polyurethane coating and the increase of the pulling-speed are increasing the ‘stent pull-off’ force. During the test interval of the pull-off speed, the ‘stent pull-off’ force for the Chronoflex®-coated stents increased from 0.45 N/mm to 0.76 N/mm.
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Aldous, Allison R. "Nitrogen retention by Sphagnum mosses: responses to atmospheric nitrogen deposition and drought". Canadian Journal of Botany 80, n.º 7 (1 de julio de 2002): 721–31. http://dx.doi.org/10.1139/b02-054.
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Sphagnum mosses are assumed to be effective at acquiring low amounts of nitrogen (N) in precipitation to support annual growth. However, N concentrations in precipitation have increased from anthropogenic sources over the last 150 years. I hypothesized that N retention from wet atmospheric deposition decreases with increased N availability, by comparing Sphagnum mosses in a high N deposition region in the Adirondack Park, New York, to a low-deposition region in eastern Maine. A 15NH415NO3 tracer was applied to mosses in both regions, and retention after 24 h was estimated. Nitrogen retention ranged from 50 to 90% of N applied. Most 15N was recovered from the apical capitula and upper stems. Nitrogen retention was greater in the Maine sites in 1998. However, in 1999, a drought year, particularly in Maine, N retention was less in Maine than in New York. The drier climate appeared to lower N retention, possibly through its physiological effects on the mosses. Although atmospheric deposition might be the only exogenous source of N, it satisfied only a small fraction of N required for annual growth. These data suggest that internal cycling processes, such as mineralization, may be much more important N sources to support Sphagnum growth.Key words: Sphagnum mosses, atmospheric nitrogen deposition, nitrogen-use efficiency, nitrogen retention, peatlands, bogs, drought.
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Alghunaim, Abdullah, Eric T. Brink, Eli Y. Newby y Bi-min Zhang Newby. "Retention of poly(N-isopropylacrylamide) on 3-aminopropyltriethoxysilane". Biointerphases 12, n.º 2 (junio de 2017): 02C405. http://dx.doi.org/10.1116/1.4982248.
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González, Francisco R. "Interpreting the gas chromatographic retention of n-alkanes". Journal of Chromatography A 873, n.º 2 (marzo de 2000): 209–19. http://dx.doi.org/10.1016/s0021-9673(99)01306-0.
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Staver, Kenneth W. "Increasing N Retention in Coastal Plain Agricultural Watersheds". Scientific World JOURNAL 1 (2001): 207–15. http://dx.doi.org/10.1100/tsw.2001.375.
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Historically, N availability has limited agricultural production as well as primary production in coastal waters. Prior to the middle of the last century, N available for grain production generally was limited to that supplied by previous legume crops, released from soil organic matter, or returned to the soil in animal wastes. The development of infrastructure to produce relatively low-cost inorganic N fertilizers eliminated the need to focus management of the entire agricultural system on increasing soil N availability. Increased N availability has contributed to dramatic increases in agricultural production but also has led to increased losses of both N and C from agricultural systems. N losses from cropland have been linked to increased algal production in the Chesapeake Bay, with N loss from cropland estimated to be the primary N input to the Bay from Coastal Plain regions of the watershed. The decade-long effort to reduce these losses has focused on reducing agricultural N use, but this strategy has yet to yield apparent reductions in N loadings to Coastal Plain tributaries. Although nitrate leaching losses are often attributed to inefficient use of N inputs, soil nitrate data indicate that both corn and soybeans can utilize nearly all available soil nitrate during periods of active growth. However, both crops tend to stop utilizing nitrate before mineralization has ceased, resulting in a late season buildup of root zone nitrate levels and significant leaching losses even when no N was applied. Reducing nitrate losses due to the inherent N inefficiency of summer annual grain crops will require the addition of winter annual crops to rotations or changes in weed management approaches that result in plant N uptake capacity being more closely matched to soil microbial N processes.
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Anes, Vitor, Cristina B. Neves, Valeria Bostan, Sérgio B. Gonçalves y Luís Reis. "Evaluation of the Retentive Forces from Removable Partial Denture Clasps Manufactured by the Digital Method". Applied Sciences 13, n.º 14 (11 de julio de 2023): 8072. http://dx.doi.org/10.3390/app13148072.
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The purpose of this study was to evaluate the retentive forces over time of removable partial denture clasps fabricated by the digital method. Occlusal rest seats were fabricated on three premolar teeth fixed in acrylic blocks (9 × 20 × 40 mm). Digitization of the teeth was performed using a laboratory scanner (Zirkonzahn Scanner S600 GmbH, Gais, Italy). After the analysis and determination of the insertion axis, two types of clasps with mesial occlusal rests were designed per tooth: the back-action and the reverse back-action clasps, using the Partial Planner Zirkonzahn program. The file was sent for fabrication of six metal clasps from a cobalt-chromium SP2 alloy in the EOSINT M270 system by a direct laser sintering process. The Instron 5544 universal testing machine was used to perform 20,000 cycles of clasp insertion and removal in the corresponding tooth with a load cell of 100 N and a speed of 2.5 mm/s. The retentive force was recorded for each of the 1000 cycles, and the change in retention over time was calculated. Statistical analysis was performed using the nonparametric Mann–Whitney test and a significance level of 5%. At 16,000 cycles, a maximum change in retention of 3.74 N was recorded for the back-action clasps and a minimum of −24.28 N at 1000 cycles for the reverse back-action clasps. The reverse back-action clasps exhibited statistically significant lower change in retention than the reverse-action clasps at 4000 and 5000 cycles. No differences were observed in the remaining cycles. During the 20,000 cycles, the change in retention was low regardless of the type of clasp. For most cycles, there were no differences in the change in retention between the two types of clasps.
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Sharaf, M. Y., Asharaf Eskander y Mohamed Afify. "Novel PEEK Retentive Elements versus Conventional Retentive Elements in Mandibular Overdentures: A Randomized Controlled Trial". International Journal of Dentistry 2022 (28 de febrero de 2022): 1–9. http://dx.doi.org/10.1155/2022/6947756.
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Background. Many patients suffer from lack of retention of conventional mandibular overdentures due to loss of clip retention over time. Computer-aided design-computer-aided manufacturing (CAD-CAM) milled polyether ether ketone (PEEK) materials may be used for the construction of retentive housing and clips for improving retention of implant-supported overdentures. Objective. To compare retention and patient satisfaction of implant-supported mandibular overdentures retained by conventional nylon clip and metal housings for ball attachments versus PEEK clip and housings. Methods. Twenty-two participants were divided into 2 equal groups (n = 11). The conventional group received implant-supported mandibular overdentures retained by metal housings and nylon retentive elements, while the PEEK group received implant-supported mandibular overdentures retained by PEEK retentive elements and housings. The PEEK retentive elements were made using computer-aided design and computer-aided manufacturing (CAD-CAM). The evaluation included measuring the retention by applying a gradual pulling up force by force meter and patient satisfaction with a 7-point visual analog scale (VAS) at overdenture insertion and 3, 6, and 12 months subsequently by a research interviewer. Results. The PEEK group showed statistically significantly increased retention force ( P < 0.05 ) at the time of insertion (37.6/17.79) and after 3 months (33.9/16.78), 6 months (32.7/15.97), and 12 months (31.65/13.05). The conventional group had a statistically significantly higher mean overall satisfaction ( P < 0.05 ) at the time of insertion (65/82.18). No statistically significant difference was found after 3 months (87.81/84.72). The PEEK group showed statistically significantly higher mean overall satisfaction ( P < 0.05 ) after 6 months (86.36/80.18) and 12 months (85.45/79.54). Conclusions. According to the results of this study, the PEEK retentive material provided more retention than did the conventional material and led to improved patient satisfaction. The study was registered at clinical trials.gov (https://clinicaltrials.gov/ct2/show/NCT05079048).
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García García, V., R. Gómez, M. R. Vidal-Abarca y M. L. Suárez. "Nitrogen retention in natural Mediterranean wetlands affected by agricultural runoff". Hydrology and Earth System Sciences Discussions 6, n.º 4 (6 de agosto de 2009): 5341–75. http://dx.doi.org/10.5194/hessd-6-5341-2009.
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Abstract. Nitrogen retention efficiency in natural Mediterranean wetlands affected by agricultural runoff was quantified and the effect of season and hydrological/chemical loading was examined from March 2007 to June 2008 in two wetland-streams located in Southeast Spain. Nitrate-N (NO3−-N), ammonium-N (NH4+-N), total organic nitrogen-N (TON-N) and chloride (Cl−) concentrations were analyzed to calculate nitrogen retention efficiencies. These wetlands consistently reduced water nitrogen concentration throughout the year with higher values for NO3−-N (72.3%), even though the mean values of inflow NO3−-N concentrations were above 20 mg l−1. Additionally, they usually acted as sinks for TON-N (45.4%), but as sources for NH4+-N. Over the entire study period, the Taray and Parra wetlands were capable of removing a mean value of 1.6 and 0.8 kg NO3−-N a day−1, respectively. Retention efficiencies were not affected by temperature variation and did not follow a seasonal pattern. The temporal variability for NO3−-N retention efficiency was positively and negatively explained by the net hydrologic retention and the inflow NO3−-N concentration (R2adj=0.832, p<0.001), respectively. TON-N retention efficiency was only positively explained by the net hydrologic retention (R2adj=0.1997, p<0.05). No significant regression model was found for NH4+-N. Finally, the conservation of these Mediterranean wetland-streams may act as a tool to not only improves the surface water quality in agricultural catchments, but to also achieve a good ecological status for surface waters, this being the Water Framework Directive's ultimate purpose.
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García-García, V., R. Gómez, M. R. Vidal-Abarca y M. L. Suárez. "Nitrogen retention in natural Mediterranean wetland-streams affected by agricultural runoff". Hydrology and Earth System Sciences 13, n.º 12 (10 de diciembre de 2009): 2359–71. http://dx.doi.org/10.5194/hess-13-2359-2009.
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Abstract. Nitrogen retention efficiency in natural Mediterranean wetland-streams affected by agricultural runoff was quantified and the effect of the temporal variability and hydrological/chemical loading was examined from March 2007 to June 2008 in two wetland-streams located in Southeast Spain. Nitrate-N (NO−3-N), ammonium-N (NH+4-N), total nitrogen-N (TN-N), total organic nitrogen-N (TON-N) and chloride (Cl−) concentrations were analyzed to calculate nitrogen retention efficiencies. These wetland-streams consistently reduced water nitrogen concentration throughout the year with higher values for NO−3-N (72.3%), even though the mean value of inflow NO−3-N concentrations was above 20 mg l−1. Additionally, they usually acted as sinks for TON-N (8.4%), but as sources for NH+4-N. Over the entire study period, the Taray and Parra wetland-streams were capable of removing on average 1.6 and 0.8 kg NO−3-N a day−1, respectively. Retention efficiencies were not affected by temperature variation. NO−3-N retention efficiency followed a seasonal pattern with the highest retention values in summer (June–September). The temporal variability for NO−3-N retention efficiency was positively and negatively explained by the hydrologic retention and the inflow NO−3-N concentration (R2adj=0.815, p<0.01), respectively. No significant regression model was found for TON-N and NH+4-N. Finally, the conservation of these Mediterranean wetland-streams may help to not only improve the surface water quality in agricultural catchments, but to also achieve good ecological status for surface waters, this being the Water Framework Directive's ultimate purpose.
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Yahya, Nur Syahina, Gaddafi Ismaili, Meekiong Kalu, Mohd Effendi Wasli, Iskanda Openg, Noor Azland Jaimudin, Mohamad Zain Hashim, Ahmad Nurfaidhi Rizalman, Hamden Mohammad y Khairul Khuzaimah Abdul Rahim. "The Mechanical Strength Properties, Treatability Retention and Hazard Classification of Treated Small-Clear Fast-Growing Acacia mangium Superbulk at Different Age Groups". Forests 14, n.º 8 (26 de julio de 2023): 1529. http://dx.doi.org/10.3390/f14081529.
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The slow growth rate of primer species has affected the supply available to accommodate the market demand. To overcome these problems, a study was carried out to fully utilise fast-growing timber as the primary resource to ensure the demand for timber logs continues. This paper aimed to determine mechanical strength properties, treatability retention, and hazard classification of 7-, 10- and 13-year-old small-clear samples of Acacia mangium superbulk collected from Daiken Plantation Sdn. Bhd. Bintulu, Sarawak, following treatment with 10% copper chrome arsenic. As a result of this study, the maximum strength was obtained from the 10-year-old age group, with the modulus of rupture (MOR), the modulus of elasticity (MOE), and compression parallel to the grain values of small-clear treated Acacia mangium superbulk reaching 118.76 N/mm2, 15,020 N/mm2, and 57.82 N/mm2, respectively. In addition, the treatability retentions obtained were 149.27 L/m3, 147.25 L/m3, and 141.09 L/m3, which were recorded from the 7-, 10-, and 13-year-old samples, respectively. Meanwhile, the dry-salt retentions obtained from the 7-, 10- and 13-year-old samples were 14.93 kg/m3, 14.73 kg/m3, and 14.11 kg/m3, respectively. Hence, this species is classified as moderately difficult to treat under CCA (treatability retention: 80–160 L/m3) and is categorised under the hazard class of H4 (dry salt retention: 12–16 kg/m3).
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Idroes, Rinaldi. "ALKYLARYLKETONE HOMOLOGOUS SERIES FOR DETERMINATION OF KOVATS RETENTION INDICES WITH RP-HPLC USING ACETONITRILE/WATER SYSTEM". Indonesian Journal of Chemistry 10, n.º 1 (21 de junio de 2010): 58–63. http://dx.doi.org/10.22146/ijc.21480.
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Some factors such as the changes of the stationary phase, temperature, pH-value, mobile-phase composition and flow rate play a crucial role in effecting the sensitivity of retention times in high performance liquid chromatography (HPLC) system. Utilizing a retention index system is one of the methods to minimize those effects. Besides the mentioned factors, dead-time influences on determining the retention index as well. In comparison with Gas Chromatography (GC), the retention Index determination method in HPLC is still widely discussed, due to the difficulty of utilizing n-alkane as standard. In addition, the solutes in HPLC interact with the mobile-phase, thus the retention behavior also depend on the mobile-phase. Actually, It is difficult to use n-alkanes in HPLC as standards in case of some considerable problems, due to they are very non polar but also large retention times which lack of chromophores. Therefore, using n-alkane in routine analysis could be inconvenient. In comparison with n-alkanes, the alkylarylketones homologous series are stable compounds, commercially available and easily detected by a UV detector. This paper introduces Determination of Kovats Retention Index in the HPLC using Alkylarylketone homologous series and then is connected with n-alkane as a frame of reference. Steroids were used as test substance for calculating Kovats retention index values in acetonitrile/water system. Keywords: Kovats Retention Index, RP- HPLC, n-alkane, alkylarylketone
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Dwivedi, C. B. "Reward-induced arousal differences in retention". Personality and Individual Differences 11, n.º 7 (enero de 1990): 685–91. http://dx.doi.org/10.1016/0191-8869(90)90253-n.
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Alikhasi, Marzieh, Ahmad Rohanian, Safoura Ghodsi y Amin Mohammadpour Kolde. "Digital versus conventional techniques for pattern fabrication of implant-supported frameworks". European Journal of Dentistry 12, n.º 01 (enero de 2018): 071–76. http://dx.doi.org/10.4103/ejd.ejd_314_17.
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ABSTRACT Objective: The aim of this experimental study was to compare retention of frameworks cast from wax patterns fabricated by three different methods. Materials and Methods: Thirty-six implant analogs connected to one-piece abutments were divided randomly into three groups according to the wax pattern fabrication method (n = 12). Computer-aided design/computer-aided manufacturing (CAD/CAM) milling machine, three-dimensional printer, and conventional technique were used for fabrication of waxing patterns. All laboratory procedures were performed by an expert-reliable technician to eliminate intra-operator bias. The wax patterns were cast, finished, and seated on related abutment analogs. The number of adjustment times was recorded and analyzed by Kruskal–Wallis test. Frameworks were cemented on the corresponding analogs with zinc phosphate cement and tensile resistance test was used to measure retention value. Statistical Analysis Used: One-way analysis of variance (ANOVA) and post hoc Tukey tests were used for statistical analysis. Level of significance was set at P < 0.05. Results: The mean retentive values of 680.36 ± 21.93 N, 440.48 ± 85.98 N, and 407.23 ± 67.48 N were recorded for CAD/CAM, rapid prototyping, and conventional group, respectively. One-way ANOVA test revealed significant differences among the three groups (P < 0.001). The post hoc Tukey test showed significantly higher retention for CAD/CAM group (P < 0.001), while there was no significant difference between the two other groups (P = 0.54). CAD/CAM group required significantly more adjustments (P < 0.001). Conclusions: CAD/CAM-fabricated wax patterns showed significantly higher retention for implant-supported cement-retained frameworks; this could be a valuable help when there are limitations in the retention of single-unit implant restorations.
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Kozlik, Petr, Katarina Molnarova, Tomas Jecmen, Tomas Krizek y Zuzana Bosakova. "Prediction of Intact N-Glycopeptide Retention Time Windows in Hydrophilic Interaction Liquid Chromatography". Molecules 27, n.º 12 (9 de junio de 2022): 3723. http://dx.doi.org/10.3390/molecules27123723.
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Analysis of protein glycosylation is challenging due to micro- and macro-heterogeneity of the attached glycans. Hydrophilic interaction liquid chromatography (HILIC) is a mode of choice for separation of intact glycopeptides, which are inadequately resolved by reversed phase chromatography. In this work, we propose an easy-to-use model to predict retention time windows of glycopeptides in HILIC. We constructed this model based on the parameters derived from chromatographic separation of six differently glycosylated peptides obtained from tryptic digests of three plasma proteins: haptoglobin, hemopexin, and sex hormone-binding globulin. We calculated relative retention times of different glycoforms attached to the same peptide to the bi-antennary form and showed that the character of the peptide moiety did not significantly change the relative retention time differences between the glycoforms. To challenge the model, we assessed chromatographic behavior of fetuin glycopeptides experimentally, and their retention times all fell within the calculated retention time windows, which suggests that the retention time window prediction model in HILIC is sufficiently accurate. Relative retention time windows provide complementary information to mass spectrometric data, and we consider them useful for reliable determination of protein glycosylation in a site-specific manner.
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Mishra, Khushbu. "Evaluation of change in implant abutment after teeth surface modifications". Bioinformation 17, n.º 1 (31 de enero de 2021): 157–61. http://dx.doi.org/10.6026/97320630017157.
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The surface modifications in teeth increase the retentive strength of cemented castings by providing micro as well as macro retentive ridge and groove patterns. Restoring the dental implants with cement-retained prosthesis is well known. Therefore, it is of interest to compare retentive property of implant abutments with and without circumferential grooves. Hence, 20 straight shoulder type titanium abutments were with abutment screws as well as prefabricated plastic copings and corresponding 12 mm-long stainless steel laboratory implant analogs were used. The abutments were divided into two subgroups of 10 abutments each: without grooves and with grooves. After thermocycling and storing the cemented abutments in water at 37°C water for 6 days they were assembled in the Universal testing machine and subjected to a pullout test (retention) at a crosshead speed of 5.0mm/min to record forces in Newton. Data suggest that the addition of grooves increased the retention. The mean retentive forces of standard machined abutments (plain) cemented with Resin modified GIC showed 339.34 N. Retention increased by 667.39N after addition of circumferential grooves. The surface modification of an implant abutment by means of circumferential grooves is an effective method of improving the retention of cast crowns cemented with resin modified GIC especially in short abutments.
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Zhao, Li Hong, Xia Lin Liao, Bei Hai He, Yuan Jun Yao y Feng Lan Wang. "Synergetic Performance of Retention Aids on Reconstituted Tobacco by Papermaking Process". Advanced Materials Research 549 (julio de 2012): 605–9. http://dx.doi.org/10.4028/www.scientific.net/amr.549.605.
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In this work, the effects of four kinds of additives including polyethyleneimine, carboxymethylcellulose, guar gum, and chitosan on the retention performance of reconstituted tobacco pulp and strength character of final base sheet were discussed. The results showed that the filler retention efficiency and first pass retention efficiency increased by 17.7% and by 5.8% at chitosan dosage of 0.2%, respectively. Moreover, the tensile index showed a distinct increase in chitosan retention system. The largest strength index was found to be in carboxymethylcellulose retention system, the tensile index was increased from 6.5 N•m/g to 8.67 N•m/g, and the wet tensile index was increased from 0.37 N•m/g to 0.51 N•m/g.
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Kong, Dejie, Chengjie Ren, Gaihe Yang, Nana Liu, Jiao Sun, Jinxia Zhu, Guangxin Ren y Yongzhong Feng. "Long-Term Wheat-Soybean Rotation and the Effect of Straw Retention on the Soil Nutrition Content and Bacterial Community". Agronomy 12, n.º 9 (7 de septiembre de 2022): 2126. http://dx.doi.org/10.3390/agronomy12092126.
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Straw retention and wheat-soybean rotation play critical role in maintaining soil quality. However, the correlation between bacterial diversity and community structure, and soil nutrients is unknown, and a systematic understanding of their responses to straw retention is lacking. In the field experiment, the straw retention treatments included no straw (NS), half straw (HS), and total straw (TS) retention during long-term wheat-soybean rotation. The mean contents of soil total nitrogen (TN), nitrate-N (NO3−-N), and microbial biomass nitrogen (MBN) increased by 15.06%, 21.10%, and 38.23%, respectively, with straw retention relative to NS, while that of ammonium-N (NH4+-N) reduced by 3.68%. The concentration of carbon components increased as straw retention increased. The levels of soil dissolved organic carbon (DOC), microbial biomass carbon (MBC), and soil organic carbon (SOC) increased by 4.34%, 7.63%, and 9.34%, respectively, with straw retention relative to NS. Soil bacterial alpha diversity was reduced with straw retention. Soil pH and nutrient content were identified as the main factors affecting the soil microbial diversity and structure at the phylum level. Accordingly, straw retention and soybean-wheat rotation enable sustainable agriculture in the dryland of northern China.
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van’t Veen, Sofie G. M. van’t, Jonas Rolighed, Jane R. Laugesen, Gitte Blicher-Mathiesen y Brian Kronvang. "High Spatial Resolution Nitrogen Emission and Retention Maps of Three Danish Catchments Using Synchronous Measurements in Streams". Water 15, n.º 3 (27 de enero de 2023): 498. http://dx.doi.org/10.3390/w15030498.
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We investigated the utility of using synchronous measurements to create nitrogen (N) emission and retention maps of agricultural areas. Total N (TN) emissions from agricultural areas in three different Danish pilot catchments (1800–3737 ha) and within sub-catchments (100–1200 ha) were determined by a source apportionment approach. Intensive daily (main gauging stations) and fortnightly (synchronous stations) monitoring of discharge, TN, and nitrate-N (NO3-N) concentrations was conducted for two years. The groundwater N retention was calculated as the difference between a model-calculated NO3-N leaching from agricultural fields and the calculated agricultural N emission. The average annual N leaching and N emission in the three catchments amounted to 68, 48, and 58 kg N/ha and 6, 30, and 40 kg N/ha, respectively. The N retention in groundwater in the three catchments, calculated based on either TN or NO3-N emissions, amounted to 26 and 44%, 44 and 57%, and 93 and 97%, respectively, with large variations within two of the main catchments. From this study, we conclude that synchronous measurements in streams provide a good opportunity for developing local N emission and N retention maps. However, NO3-N should be used when dealing with N retention calculation at the finer resolution scale of 100–300 ha catchments.
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Cao, Zhi Ling, Wei Wei Liu, Jian Jun Xiong, Na Qu, Hong Xia Li y Guo Wei Yao. "Synthesis and Properties of N,N-Dimethyl-O-Quaternary Ammonium Chitosan". Advanced Materials Research 152-153 (octubre de 2010): 1337–41. http://dx.doi.org/10.4028/www.scientific.net/amr.152-153.1337.
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N,N-dimethyl-O-quaternary ammonium chitosan(NNQAC) was synthesized from chitosan by N-dimethylation then quaternized by 2,3-epoxy propyl trimethyl ammonium chloride. The structure of NNQAC was characterized by FTIR. Properties of quaternary ammonium chitosans, including solubility, antimicrobial activity, water-absorption and water-retention ability, were investigated. The results showed that NNQAC was water–soluble in neutral and basic environments. The moisture-absorption and retention abilities of NNQAC were higher than that of chitosan and equivalent to hyaluronic acid. The antibacterial activities of NNQAC were tested against Bacillus subtilis, Escherichia coli and Staphylococcus aureus. In water medium, NNQAC exhibited MIC values in the range of 10 to 2.5 μg/mL.
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Stålnacke, P., A. Pengerud, A. Vassiljev, E. Smedberg, C. M. Mörth, H. E. Hägg, C. Humborg y H. E. Andersen. "Nitrogen surface water retention in the Baltic Sea drainage basin". Hydrology and Earth System Sciences 19, n.º 2 (23 de febrero de 2015): 981–96. http://dx.doi.org/10.5194/hess-19-981-2015.
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Abstract. In this paper, we estimate the surface water retention of nitrogen (N) in all the 117 drainage basins to the Baltic Sea with the use of a statistical model (MESAW) for source apportionment of riverine loads of pollutants. Our results show that the MESAW model was able to estimate the N load at the river mouth of 88 Baltic Sea rivers, for which we had observed data, with a sufficient degree of precision and accuracy. The estimated retention parameters were also statistically significant. Our results show that around 380 000 t of N are annually retained in surface waters draining to the Baltic Sea. The total annual riverine load from the 117 basins to the Baltic Sea was estimated at 570 000 t of N, giving a total surface water N retention of around 40%. In terms of absolute retention values, three major river basins account for 50% of the total retention in the 117 basins; i.e. around 104 000 t of N are retained in Neva, 55 000 t in Vistula and 32 000 t in Oder. The largest retention was found in river basins with a high percentage of lakes as indicated by a strong relationship between N retention (%) and share of lake area in the river drainage areas. For example in Göta älv, we estimated a total N retention of 72%, whereof 67% of the retention occurred in the lakes of that drainage area (Lake Vänern primarily). The obtained results will hopefully enable the Helsinki Commission (HELCOM) to refine the nutrient load targets in the Baltic Sea Action Plan (BSAP), as well as to better identify cost-efficient measures to reduce nutrient loadings to the Baltic Sea.
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Stålnacke, P., A. Pengerud, A. Vassiljev, E. Smedberg, C. M. Mörth, H. E. Hägg, C. Humborg y H. E. Andersen. "Nitrogen surface water retention in the Baltic Sea drainage basin". Hydrology and Earth System Sciences Discussions 11, n.º 9 (26 de septiembre de 2014): 10829–58. http://dx.doi.org/10.5194/hessd-11-10829-2014.
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Abstract. In this paper, we estimate the surface water retention of nitrogen (N) in all the 117 drainage basins to the Baltic Sea with the use of a statistical model (MESAW) for source apportionment of riverine loads of pollutants. Our results show that the MESAW model was able to estimate the N load at the river mouth of 88 Baltic Sea rivers, for which we had observed data, with a sufficient degree of precision and accuracy. The estimated retention parameters were also statistically significant. Our results show that around 380 000 t of N are annually retained in surface waters draining to the Baltic Sea. The total annual riverine load from the 117 basins to the Baltic Sea was estimated to 570 000 t of N, giving a total surface water N retention of around 40%. In terms of absolute retention values, three major river basins account for 50% of the total retention in the 117 basins; i.e. around 104 000 t of N is retained in Neva, 55 000 t in Vistula and 32 000 t in Oder. The largest retention was found in river basins with a high percentage of lakes as indicated by a strong relationship between N retention (%) and share of lake area in the river drainage areas. For example in Göta älv, we estimated a total N retention of 72%, whereof 67% of the retention occurred in the lakes of that drainage area (Lake Vänern primarily). The obtained results will hopefully enable the Helsinki Commission (HELCOM) to refine the nutrient load targets in the Baltic Sea Action Plan (BSAP), as well as to better identify cost-efficient measures to reduce nutrient loadings to the Baltic Sea.
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Liu, Meibing, Xingwei Chen, Ying Chen, Lu Gao y Haijun Deng. "Nitrogen Retention Effects under Reservoir Regulation at Multiple Time Scales in a Subtropical River Basin". Water 11, n.º 8 (14 de agosto de 2019): 1685. http://dx.doi.org/10.3390/w11081685.
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Reservoirs are an important nitrogen sink as a result of their retention effect, but their retention performance may vary with hydrologic conditions with time-varying characteristics, which also change them from being a sink to source over time. This study uses a coupled modelling system (Soil and Water Assessment Tool (SWAT) and a two-dimensional hydrodynamic and water quality model (CE-QUAL-W2) to analyze the nitrogen retention effect and influential factors at annual, monthly, and daily scales in Shanmei Reservoir in southeast China. The results showed that there was a positive retention effect of total nitrogen (TN), nitrate-nitrogen (NO3-N) and ammonia nitrogen (NH4-N) in most years, with average retention rates up to 12.7%, 7.83% and 26.17%, respectively. The reservoir serves mainly as a nitrogen sink at an annual scale. The monthly retention performances of TN and NO3-N were observed during the wet season (April–October) with higher water temperature and lower velocity, while a release effect occurred during the dry season (November–March). For NH4-N, which is prone to nitrification, the retention effect lasted longer, from May to December. The daily nitrogen retention process changed more dramatically, with the retention rate varying from −292.49 to 58.17%. During the period of dispatch, the regulated discharge was the primary factor of daily retention performance, while the hydraulic residence time, velocity and water level were all significantly correlated with nitrogen retention during the period without dispatch.
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MAY, DEBORAH C., DEBORAH K. KUNDERT y DONNA BRENT. "Does Delayed School Entry Reduce Later Grade Retentions and Use of Special Education Services?" Remedial and Special Education 16, n.º 5 (septiembre de 1995): 288–94. http://dx.doi.org/10.1177/074193259501600505.
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The practice of delaying children's entry into a kindergarten program 1 year beyond the traditional chronolgical age of their classmates is a controversial issue. although this practice has been said to reduce the need for grade retentions and special education services, the research literature has yielded contradictory results about the effects of delayed entry on students. the present study examined the effects of delayed entry in one suburban new york school district on later elementaryschool grade retention and special education service rates. in addition, the influence of gender on the practice of delayed entry was investigated. the sample for this study consisted of all students (n = 3,238) who were enrolled in grades 1 through 12; from this, a subsample of all children (n = 279) who had delayed school entry were identified, and their records were examined for future retentions and use of special education services. it was found that students who delayed school entry were most often male and were placed in special education programs in significantly higher proportions than nondelayed-entry students. no significant effect of delayed entry was noted for retention.
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Beusen, A. H. W., A. F. Bouwman, L. P. H. Van Beek, J. M. Mogollón y J. J. Middelburg. "Global riverine N and P transport to ocean increased during the twentieth century despite increased retention along the aquatic continuum". Biogeosciences Discussions 12, n.º 23 (15 de diciembre de 2015): 20123–48. http://dx.doi.org/10.5194/bgd-12-20123-2015.
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Abstract. Various human activities, including agriculture, water consumption, river damming, and aquaculture, have intensified over the last century. This has had a major impact on nitrogen (N) and phosphorus (P) cycling in global continental waters. In this study, we use a coupled nutrient-input, hydrology, in-stream nutrient retention model to quantitatively track the changes in the global freshwater N and P cycles over the 20th century. Our results suggest that, during this period, the global nutrient delivery to streams increased from 34 to 64 Tg N yr−1 and from 5 to 9 Tg N yr−1. Furthermore, in-stream retention and removal grew from 14 to 27 Tg N yr−1 and 3 to 5 Tg N yr−1. One of the major cause of increased retention is the growing number of reservoirs which now account for 24 and 22 % of global N and P retention/removal in freshwater systems, respectively. This increase in nutrient retention could not balance the increase in nutrient delivery to rivers with the consequence that river nutrient transport to the ocean increased from 19 to 37 Tg N yr−1 and from 2 to 4 Tg N yr−1. Human activities have also led to a global increase in the molar N : P ratio in freshwater bodies.
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Garciá-Raso, A., M. I. Páez, I. Martínez-Castro, J. Sanz y M. M. Calvo. "Gas chromatographic retention of carbohydrate trimethylsilyl ethers". Journal of Chromatography A 607, n.º 2 (agosto de 1992): 221–25. http://dx.doi.org/10.1016/0021-9673(92)87079-n.
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Deste Gokay, Gonca, Serhat Emre Ozkir, Thomas Gerhard Wolf, Gulsum Gokcimen, Nergiz Rona, Mehmet Bicer y Burak Yilmaz. "The Effect of Denture Cleansing Solutions on the Retention of Precision Attachments: An In Vitro Study". International Journal of Environmental Research and Public Health 19, n.º 7 (5 de abril de 2022): 4345. http://dx.doi.org/10.3390/ijerph19074345.
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This study aimed to investigate the effect of different cleansing solutions on the retention of precision attachments. A precision attachment patrix was embedded into acrylic resin and the matrix was placed onto the patrix. The red (high retention, 8 N), yellow (regular retention, 6 N), and green (reduced retention, 4 N) plastic matrixes of the attachments (n = 32) were soaked in three different denture cleansing solutions (sodium laureth sulfate, sodium bicarbonate-sodium perborate, sodium bicarbonate) for a duration simulating 6 months of clinical use. The control group was soaked in tap water. A universal testing machine was used to measure the retention values of attachments after they were soaked in denture cleansers. The retention values were compared among the groups with repeated-measures analysis of variance followed by the Tukey HSD test (p = 0.05). Yellow attachments were affected by sodium laureth sulfate, sodium bicarbonate-sodium perborate, and water (p = 0.012). Green attachments’ retention increased after immersion in sodium laureth sulfate (p = 0.04) and water (p = 0.02). Red attachments’ retention increased after immersion in sodium laureth sulfate or sodium bicarbonate-sodium perborate (p = 0.045). Water did not affect the retention of red attachments. Because sodium bicarbonate tablets did not affect the retention of attachments, clinicians may recommend their use as a cleanser. Clinicians also may inform patients using fixed and removable partial prostheses with precision attachments of a possible increase in retention after the use of sodium laureth sulfate or when using sodium bicarbonate-sodium perborate with yellow and red attachments.
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Li, Sha, Tiandan Li, Xiaochao Hu, Yong Yang, Yangyi Huang y Kai He. "A Neglected Issue: Stationary Phase Retention Determination of Classic High-Speed Counter-Current Chromatography Solvent Systems". Separations 9, n.º 11 (8 de noviembre de 2022): 357. http://dx.doi.org/10.3390/separations9110357.
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Obtaining an ideal solvent system for target compounds is still an obstacle to the wide application of high-speed counter-current chromatography (HSCCC). The partition coefficient and retention of the stationary phase are two key parameters for solvent system selection. The retention of the stationary phase of the solvent system is roughly judged by settling time using a test tube, which is subjective and inaccurate. In this study, we demonstrated that high-resolution separation of HSCCC is tightly connected with the retention of the stationary phase. Notably, unlike the in vitro test of settling time, we investigated the retention of the stationary phase of classical biphasic solvent systems by a TBE300C HSCCC apparatus. Our results revealed that settling time is not always inversely proportional to the retention of the stationary phase. The n-hexane–ethylacetate–methanol–water solvent systems showed the highest correlation coefficient of settling time and retention of the stationary phase (r = −0.91, n = 16). N-heptane–n-butanol–acetonitrile–water solvent system showed the lowest correlation coefficient (r = −0.26, n = 7). These results may be helpful for HSCCC solvent system selection and accelerate the application of this technique.
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Bartelt, Robert J., Melody L. Moats y Larry L. Jackson. "Relationships between structure and chromatographic retention for n-alkadienes". Journal of Chromatography A 366 (enero de 1986): 27–37. http://dx.doi.org/10.1016/s0021-9673(01)93452-1.
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Slesak, Robert A., Timothy B. Harrington y Stephen H. Schoenholtz. "Soil and Douglas-fir (Pseudotsuga menziesii) foliar nitrogen responses to variable logging-debris retention and competing vegetation control in the Pacific Northwest". Canadian Journal of Forest Research 40, n.º 2 (febrero de 2010): 254–64. http://dx.doi.org/10.1139/x09-188.
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Experimental treatments of logging-debris retention (0%, 40%, or 80% surface coverage) and competing vegetation control (initial or annual applications) were installed at two sites in the Pacific Northwest following clearcutting Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii) stands to assess short-term effects on tree N acquisition, soil N supply, and total soil N. Vegetation control treatments began in the first year after harvest, and logging-debris manipulations were installed 2 years after harvest. Annual vegetation control increased foliar N concentration and content in most years at both sites, which was associated with higher available soil N and increased soil water content. Logging-debris retention treatments had no detectable effect on any of the foliar variables or soil available N at either site. There were no treatment effects on total soil N at the site with relatively high soil N, but total soil N increased with logging-debris retention when annual vegetation control was applied at the site with a low initial soil N pool. Competing vegetation control is an effective means to increase tree N acquisition in the initial years after planting while maintaining soil N pools critical to soil quality. The effect of logging-debris retention on tree N acquisition appears to be limited during early years of stand development, but increased soil N with heavy debris retention at certain sites may be beneficial to tree growth in later years.
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Vijjeswarapu, Annie P., Vaibhav Londhe, Mahasampath Gowri, Aruna Kekre y Nitin Kekre. "Prevalence and clinical predictors for early post-operative urinary retention in patients undergoing pelvic reconstructive surgeries: a prospective cohort study". International Journal of Reproduction, Contraception, Obstetrics and Gynecology 7, n.º 4 (27 de marzo de 2018): 1452. http://dx.doi.org/10.18203/2320-1770.ijrcog20181334.
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Background: Pelvic organ prolapse (POP) has a significant impact on quality of life. Post-operative voiding dysfunction is seen in 2.5 to 24% of patients following pelvic reconstructive surgery. Risk factors like age of the patient, size of the genital hiatus and stage of prolapse are known to be associated with early post-operative voiding disorders.Methods: This is a prospective cohort study done in Christian Medical College, Vellore over one year. Patients with stage II to IV pelvic organ prolapse who underwent pelvic reconstructive surgery were observed post operatively for covert and overt urinary retention. Inability to void accompanied by pain and discomfort is defined as overt retention. Early post-operative urinary retention (POUR) is retention of urine in the first 72 hours postoperatively. Covert retention is defined as a non-painful bladder with chronic high post void residue. Chi- square test or Fisher’s exact test was used to assess the association between the clinical predictors and early post-operative urinary retention in univariate analysis.Results: In this study, 75 patients were recruited. Nine patients had POUR. Among the patients who had post-operative urinary retention, 77.78% had stage III pelvic organ prolapse (n=7). P value was 0.042. The prevalence of early POUR after pelvic reconstructive surgery was 12.85 % (n=9). A 55.55% had covert retention (n=5) and 44.44% patients had overt retention (n=4).Conclusions: The prevalence of early POUR after pelvic reconstructive surgery was 12.85%. Stage of the prolapse was an independent predictor for early postoperative urinary retention.
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Tullis, J. Bronwyn, C. T. Whittemore y Patricia Phillips. "Compensatory nitrogen retention in growing pigs following a period of N deprivation". British Journal of Nutrition 56, n.º 1 (julio de 1986): 259–67. http://dx.doi.org/10.1079/bjn19860105.
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1. Semi-synthetic diets, with dried microbial cells (Pruteen) as the nitrogen source, were used to measure N retention in 50 kg pigs given different combinations of N intake involving periods of deprivation and enhanced supply.2. Metabolic faecal N losses were 1.92 g/d (1.26 g/kg dry matter eaten) and endogenous urinary losses were 3.96 g/d for pigs given an N intake of 6.9 g/d.3. Compensatory N retention averaging 4.2 g extra N/d was observed in pigs given enhanced N supply by diets providing 31.0, 60.4 and 93.4 g N/d. In some instances enhanced N retention was maintained for 22 d.4. Pigs given enhanced N supply by extravagant N intake did not maintain the compensatory response which had been evident initially.
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Cordero - Au Yeung, Rie Sheena y Marilyn Tiongson. "The Impact of Talent Management Practices on Organizational and Human Resources Outcomes: A Study on Philippines Department Of Foreign Affairs Talent Management Practices". International Journal of Scientific Research and Management 10, n.º 11 (23 de noviembre de 2022): 1288–301. http://dx.doi.org/10.18535/ijsrm/v10i11.sh02.
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The study examined the Philippine Department of Foreign Affairs (DFA) talent management practices and whether its practices influence its organizational and human resources outcomes. The three independent variables are talent attraction, talent development, and talent retention, while the two dependent variables are organizational and human resources outcomes. Three hundred respondents answered a 43-item questionnaire. The Pearson's Correlation analysis results show significant positive relationships between organizational outcomes and (a) talent attraction, r=.734, N=300, p < 0.001; (b) talent development, r=.699, N=300, p < 0.001, and (c) talent retention, r=.748, N=300, p < 0.001. Likewise, the analysis showed that there are significant positive relationships between human resource outcomes and (a) talent attraction, r=.753, N=300, p < 0.001; (b) talent development, r=.765, N=300, p < 0.001, and (c) talent retention, r=.808, N=300, p < 0.001. The study revealed that talent attraction, development, and retention positively influence organizational and human resources outcomes. Talent Development is the primary strength of the Department with the highest weighted mean (WM:3.71; SD:0.78), followed by Talent Attraction (WM:3.56; SD:0.81) and talent retention (WM:3.27; SD:0.90).
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Beusen, Arthur H. W., Alexander F. Bouwman, Ludovicus P. H. Van Beek, José M. Mogollón y Jack J. Middelburg. "Global riverine N and P transport to ocean increased during the 20th century despite increased retention along the aquatic continuum". Biogeosciences 13, n.º 8 (27 de abril de 2016): 2441–51. http://dx.doi.org/10.5194/bg-13-2441-2016.
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Abstract. Various human activities – including agriculture, water consumption, river damming, and aquaculture – have intensified over the last century. This has had a major impact on nitrogen (N) and phosphorus (P) cycling in global continental waters. In this study, we use a coupled nutrient-input–hydrology–in-stream nutrient retention model to quantitatively track the changes in the global freshwater N and P cycles over the 20th century. Our results suggest that, during this period, the global nutrient delivery to streams increased from 34 to 64 Tg N yr−1 and from 5 to 9 Tg P yr−1. Furthermore, in-stream retention and removal grew from 14 to 27 Tg N yr−1 and 3 to 5 Tg P yr−1. One of the major causes of increased retention is the growing number of reservoirs, which now account for 24 and 22 % of global N and P retention/removal in freshwater systems, respectively. This increase in nutrient retention could not balance the increase in nutrient delivery to rivers with the consequence that river nutrient transport to the ocean increased from 19 to 37 Tg N yr−1 and from 2 to 4 Tg P yr−1. Human activities have also led to a global increase in the molar N : P ratio in freshwater bodies.
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Pudjihastuti, E. "RETENSI N, Ca DAN P PADA KAMBING YANG DIBERI DEDAK HALUS YANG DIAUTOCLAVE DENGAN LEVEL BERBEDA". ZOOTEC 35, n.º 1 (7 de febrero de 2015): 86. http://dx.doi.org/10.35792/zot.35.1.2015.7101.
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RETENTION OF N, Ca and P in GOAT GIVEN FINE BRAN THAT OUTOCLAVED WITH DIFFERENT LEVEL. The aim of this study was to determine the effect of autoclaved fine bran use at different levels on the retention of nitrogen (N), calcium (Ca) and phosphorus (P) in goats. This study used four goats at age of 7-8 months old with body weight of 8-10 kg. Basic feed used was Brachiaria mutica grass, which added with autoclaved fine bran at different levels, as follows: R0 = Brachiaria mutica grass R1 = Brachiaria mutica grass+ 10% autoclaved fine bran R2 = Brachiaria mutica grass+ 20% autoclaved fine bran R1 = Brachiaria mutica grass+ 30% autoclaved fine bran This study used an experimental method based on the 4 x 4 Latin square design, where livestock served as row and experimental method as a line, followed by Duncan's multiple range test analysis. Results of analysis of variance showed that the treatment effect is highly significant (p <0.01) on dry matter intake, consumption and retention of N, consumption and retention of Ca and P. With Duncan's multiple range test showed that the treatment R3 was higher (p <0.01) than treatments of R2, R1 and R0 on consumption and retention of N, Ca and P. From these results, it can be concluded that the use of autoclaved fine bran up to 30% can improve the retention of N, Ca and P in goats. Keywords: Fine bran, Autoclave, Retention, Goat
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Aleisa, Khalil. "Bond Strength of Overdenture Locator Posts Cemented with Seven Luting Agents". Journal of Contemporary Dental Practice 14, n.º 4 (2013): 675–80. http://dx.doi.org/10.5005/jp-journals-10024-1384.
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ABSTRACT Statement of the problem Post retention is crucial factor in restoration survival. Posts are commonly failed due to loss of retention. It is unknown which luting agents would provide the maximum bond strength for Locator overdenture posts. Aim The aim of this study was to evaluate the bond retentive strengths of Locator overdenture posts cemented with 7 luting agents. Materials and methods One hundred and five single rooted human teeth were decoronated and randomly assigned to 7 groups (n = 15). Post spaces were prepared with Locator post drills to the depth of 6 mm. The Locator posts were cemented with Variolink II, RelyX ARC, Multilink N, RelyX Unicem, ParaCore, or MultiCore Flow resin luting agents. Zinc phosphate cement was served as control group. Specimens were stored in water at 37°C for 24 hours. Each specimen was loaded in tension in an Instron universal testing machine. The maximum force required to dislodge each Locator post was recorded. Means and standard deviations were calculated and data were statistically analyzed with one-way analysis of variance (ANOVA). Results The highest mean bond strength value for Locator posts was recorded for MultiCore® Flow group (mean = 550.1 N), while the lowest mean value was for RelyX Unicem™ resin cement group (mean = 216.8 N). A statistically significant difference in mean locator overdenture post bond strength was observed between the 7 cement types (p < 0.0001). ParaCore™ and MultiCore® Flow groups had significantly higher bond strength than all other groups, but they were not differed from each other. Conclusion Bond strength of Locator overdenture posts were influenced by the type of luting agents. MultiCore Flow and ParaCore resin cements offered the greatest retention. Clinical significance The type of luting agents had a significant effect on the retention of Locator posts. The use of Core buildup resin cements as luting agent with Locator post demonstrated the greatest retention. How to cite this article Aleisa K. Bond Strength of Overdenture Locator Posts Cemented with Seven Luting Agents. J Contemp Dent Pract 2013;14(4):675-680.
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Duvet, Sandrine, Jean Dubuisson, Myriam Ermonval, René Cacan y André Verbert. "Retention and Degradation of N-Glycoproteins in the Rough Endoplasmic Reticulum". Bioscience Reports 19, n.º 5 (1 de octubre de 1999): 491–98. http://dx.doi.org/10.1023/a:1020228725997.
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Recent studies have shown that newly synthesized proteins and glycoproteins are submitted to a quality control mechanism in the rough endoplasmic reticulum (ER). In this report we present two models: One model will illustrate a transient retention in rough ER leading to a further degradation of glycoproteins in the cytosol, (soluble alkaline phosphatase expressed in Man-P-Dol deficient CHO cells lines). The second model will illustrate a strict retention of glycoproteins in rough ER without degradation nor recycling through the Golgi (E1, E2 glycoproteins of Hepatitis C virus in stably transfected UHCV-11.4 cells and in infected Hep G2 cells). In both cases, oligomannoside structures are markers of these phenomena, either as free soluble released oligomannosides in the case of degradation, or as N-linked oligomannosides for strict retention in rough ER.
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Dikhtyar, Oksana y Ian Matt Nelson. "STRATEGIES USED BY OHIO’S NURSING HOMES TO RETAIN CERTIFIED NURSING ASSISTANTS: DO THEY WORK?" Innovation in Aging 7, Supplement_1 (1 de diciembre de 2023): 293. http://dx.doi.org/10.1093/geroni/igad104.0978.
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Abstract A low retention rate of certified nursing assistants (CNA) in nursing homes (NHs) is a known problem; it drives up facilities’ operating costs and negatively impacts the quality of care provided. The COVID-19 pandemic exacerbated this problem and left facilities scrambling to retain workers. Using data from the 2021 Ohio Biennial Survey of Long-Term Care Facilities, this study examines strategies implemented by facilities to improve retention of their CNAs. Facilities have tried to implement a variety of workplace environment changes such as allowing staff teams to manage schedule and financial benefit strategies such as longevity wage increase to improve their CNA retention. The statewide average NH retention rate was 64% for CNAs ranging between 0 and 100%. Three groups were constructed from the retention data: high or rate of 75% or higher (N = 220), medium or between 50% and 75% (N = 254), and low or under 50% (N = 145). We found that a higher proportion of low-retention facilities implemented most of these strategies compared to facilities with high and medium CNA retention rates. At the same time, we found that a higher proportion of administrators in the high retention group knew all their CNAs by name compared to the low-retention group (50.0% vs 41.7%). These findings suggest that environmental and financial strategies may not have much of an impact on retention rates, but making people feel respected and appreciated could.